1. Field of the Invention
The present invention relates to improved test apparatus for pulse code modulation-to-frequency division multiplexed telecommunications transmultiplexer apparatus.
The present invention also relates to apparatus for testing expanded bandwidth program channels in PCM channel bank equipment on a single ended basis.
2. Description of the Prior Art
In the prior art, testing of transmultiplexer apparatus is accomplished by using an analog white noise generator together with banks of shaping filters consisting of high and low pass filters, a plurality of C-message weighting filters centered at a plurality of different frequencies, and channel bandpass and bandstop filters for each channel of interest, or an entire frequency division multiplex channel bank. The PCM testing is achieved with either a PCM test set or a PCM channel bank, and a channel at a time is tested.
It is desired to test PCM channels both with standard 8 KHz sampling rates as well as 16, 24, 32, and 48 KHz sampling rates utilizing standard u-255 law PCM coding and/or A-law PCM coding. It is further desired to obtain fine frequency resolution in the range of approximately 2 Hz.
PCM generator/receiver test sets of the prior art lack programmable sample frequencies. Additionally, prior art generator/receiver test sets of the prior art have used PCM simulation or decoding and testing telecommunication equipment having coarser frequency resolution and higher harmonic content that the test set of the present invention, without the capability of programmable selectivity in testing multiple channels simultaneously.